Valve

ABSTRACT

A valve ( 1 ) for supplying fuel gas to a gas appliance comprises a valve housing ( 2 ) having a valve chamber ( 3 ) extending therethrough. Fuel gas is supplied through an inlet port ( 5 ) to the valve chamber ( 3 ) and from main and secondary outlet ports ( 6,7 ) to a burner and a pilot light jet, respectively, of the gas appliance. A primary valving member ( 35 ) and a secondary valving member ( 36 ) co-operate with a primary valve seat ( 15 ) and a secondary valve seat ( 20 ), respectively, for isolating the main and secondary outlet ports ( 6,7 ) from the inlet port ( 5 ). A main carrier member ( 30 ) carries the primary valving member ( 35 ) and is magnetically coupled to a first secondary carrier member ( 31 ) which is driven by a stepper motor ( 38 ). A second secondary carrier member ( 32 ) is magnetically coupled to the main carrier member ( 30 ) for carrying the secondary valving member ( 36 ). Electromagnetic coils ( 60,61 ) magnetically couple the first and second secondary carrier members ( 31,32 ) to the main carrier ( 30 ) so that the drive motor ( 38 ) can operate the main carrier ( 30 ) and in turn the primary and secondary valving members ( 35,36 ) for opening and closing primary and secondary communicating passageways ( 19,25 ) through the primary and secondary valve seats ( 15,20 ). Isolating the coils ( 60,61 ) from a power supply causes the first and second carrier members ( 31,32 ) to be decoupled from the main carrier ( 30 ), and first compression springs ( 65,66 ) urge the primary valving member ( 35 ) into engagement with the primary valve seat ( 15 ) while a second compression spring ( 80 ) urges the secondary valving member ( 36 ) into engagement with the secondary valve seat ( 20 ) the outlet ports ( 6,7 ) from the inlet port ( 5 ).

[0001] The present invention relates to a valve, and in particular, to asafety valve which is particularly suitable though not limited to use asa safety valve for controlling the flow of fuel gas to a gas poweredappliance, though not limited to such use.

[0002] Safety valves which are typically used for controlling the supplyof fuel gas to a gas powered appliance, for example, a gas poweredheater, a gas powered oven, a gas powered hob or the like, typicallycomprise a solenoid type operated valve. Such valves comprise a valvehousing which define a hollow interior valve chamber. An inlet port isprovided to the valve chamber, while an outlet port is provided from thevalve chamber. A valve seat is formed within the valve chamber betweenthe inlet and the outlet ports, and defines a communicating passagewaybetween the respective inlet and outlet ports. A valving member locatedwithin the valve chamber co-operates with the valve seat for closing thecommunicating passageway for in turn closing the valve. A solenoid coilco-operable with the valving member when energised urges the valvingmember out of engagement with the valve seat for opening thecommunicating passageway for opening the valve. An urging means,typically, a compression spring urges the valving member into engagementwith the valve seat when power is removed from the solenoid coil. Forsafety reasons in general two such solenoid valves are normally locatedin series in a fuel gas pipeline so that should one of the solenoidvalves fail to operate for isolating the gas powered appliance from thefuel gas supply, at least one of the solenoid valves should operate.

[0003] In general, the valving member is rigidly secured to a magneticbody of the solenoid coil, so that variation in the intensity of themagnetic field generated by the solenoid coil causes the magnetic bodyto move and in turn the valving member for opening and closing of thevalve. In general, the valving member is spring urged into the closedposition, and thus, in order to retain the valve open power must becontinuously supplied to the solenoid for so long as it is desired toretain the valve open. Furthermore, the magnetic field generated by thesolenoid coil must be of sufficient strength to hold the valving memberopen against the action of the compression spring which acts to urge thevalving member into engagement with the valve seat. This, in general,requires a relatively high current through the solenoid coil which leadsto heating of the valve as a result of power dissipation from thesolenoid coil which may be as high as 4 watts to 5 watts and in manycases even more. Additionally, such solenoid valves tend to berelatively noisy as the valving member is urged between its open andclosed positions.

[0004] Accordingly, it is an object of the present invention to providea valve, and in particular to a provide a safety valve which isparticularly suitable for use for fuel gas which overcomes the problemsof known types of valves. Although it is also an object of the presentinvention to provide a valve for other uses which overcomes the problemsof known valves.

[0005] The present invention is directed towards providing such a valve.

[0006] According to the invention there is provided a valve comprising avalve housing defining a valve chamber, the valve chamber forming aninlet chamber and an outlet chamber, a primary valve seat separating theinlet chamber from the outlet chamber and defining a primarycommunicating passageway communicating the inlet chamber with the outletchamber, a primary valving member in the valve chamber co-operating withthe primary valve seat for selectively closing the primary communicatingpassageway for isolating the outlet chamber from the inlet chamber, anda drive means for urging the primary valving member out of engagementwith the primary valve seat for opening the primary communicatingpassageway for communicating the respective inlet and outlet chambers,wherein the drive means is releasably magnetically coupled to theprimary valving member for urging the primary valving member out ofengagement with the primary valve seat, the drive means and the primaryvalving member being selectively decoupleable, and a first urging meansis provided for urging the primary valving member into engagement withthe primary valve seat when the primary valving member is decoupled fromthe drive means.

[0007] In one embodiment of the invention a secondary valve seat islocated in the outlet chamber downstream of the primary valve seat, thesecondary valve seat dividing the outlet chamber into an upstreamchamber and a downstream chamber and defining a secondary communicatingpassageway communicating the downstream chamber with the upstreamchamber, and a secondary valving member is provided in the outletchamber co-operating with the secondary valve seat for closing thesecondary communicating passageway for isolating the downstream chamberfrom the upstream chamber, the secondary valving member being releasablymagnetically coupled with the drive means and being urgeable by thedrive means out of engagement with the secondary valve seat for openingthe secondary communicating passageway for communicating the downstreamchamber with the upstream chamber when the secondary valving member ismagnetically coupled to the drive means.

[0008] In another embodiment of the invention the secondary valvingmember is selectively decoupleable from the drive means, and a secondurging means is provided for urging the secondary valving member intoengagement with the secondary valve seat when the secondary valvingmember is decoupled from the drive means.

[0009] In a further embodiment of the invention the secondary valvingmember is magnetically coupled to the drive means through the primaryvalving member.

[0010] In one embodiment of the invention the secondary valving memberis releasably magnetically coupled to the primary valving member.

[0011] In another embodiment of the invention the secondary valvingmember is selectively decoupleable from the primary valving member.Preferably, the secondary valving member is selectively decoupleablefrom the primary valving member independently of decoupling of theprimary valving member from the drive means.

[0012] Preferably, the primary and secondary valving members aresequentially urged out of engagement with the respective primary andsecondary valving seats by the drive means when the respective primaryand secondary valving members are magnetically coupled to the drivemeans.

[0013] Advantageously, the primary valving member is urged out ofengagement with the primary valve seat before the secondary valvingmember is urged out of engagement with the secondary valve seat.Advantageously, the primary valving member is carried on a main carriermember, and the drive means is co-operable with a first secondarycarrier member, the first secondary carrier member forming with the maincarrier member a magnetic circuit, and a first magnetic field generatingmeans is provided for selectively generating a magnetic field forselectively coupling the main carrier member and the first secondarycarrier member.

[0014] In one embodiment of the invention a second secondary carriermember is provided for carrying the secondary valving member, the secondsecondary carrier member forming a magnetic circuit with the maincarrier member for facilitating releasable magnetic coupling of thesecond secondary carrier member with the main carrier member.

[0015] In another embodiment of the invention a second magnetic fieldgenerating means is provided for selectively magnetically coupling thesecond secondary carrier member with the main carrier memberindependently of the magnetic coupling of the main carrier member withthe first secondary carrier member.

[0016] Preferably, the second urging means acts between the main carriermember and the second secondary carrier member, and advantageously, thesecondary valving member is resiliently mounted to the second secondarycarrier member for facilitating relative movement between the secondsecondary carrier member and the secondary valving member forfacilitating disengagement of the primary valving member from theprimary valve seat prior to disengagement of the secondary valvingmember from the secondary valve seat.

[0017] Preferably, each magnetic field generating means is anelectrically powered magnetic field generating means. Advantageously, anelectrically conductive connecting means is provided for connecting eachmagnetic field generating means to an electrical power supply externallyof the valve.

[0018] In one embodiment of the invention the respective first andsecond magnetic field generating means are independently connected tothe external power supply by the electrically conductive connectingmeans.

[0019] In another embodiment of the invention the first magnetic fieldgenerating means comprises a first electromagnetic coil associated withthe main carrier member and the first secondary carrier member.

[0020] In a further embodiment of the invention the second magneticfield generating means comprises a second electromagnetic coilassociated with the main carrier member and the second secondary carriermember.

[0021] Alternatively, the first magnetic field generating meansselectively couples the second secondary carrier member with the maincarrier member.

[0022] Advantageously, the first urging means acts between the valvehousing and the main carrier member for urging the primary valvingmember into engagement with the primary valve seat, and preferably, thefirst urging means comprises a pair of first compression springs.

[0023] In one embodiment of the invention the respective firstcompression springs are electrically conductive and are electricallymutually insulated for acting as the connecting means for connecting thefirst magnetic field generating means to the external electrical powersupply.

[0024] In an alternative embodiment of the invention the respectivefirst compression springs independently connect the respective firstand-second magnetic field generating means to the external electricalpower supply.

[0025] In one embodiment of the invention the first compression springsare concentrically mounted. Preferably, the second urging meanscomprises a second compression spring.

[0026] In one embodiment of the invention the valve chamber is anelongated chamber, and the main carrier member is an elongated memberextending longitudinally in the valve chamber through the primarycommunicating passageway from the inlet chamber to the outlet chamber.Preferably, the valve chamber is of circular transverse cross-sectiondefining a main longitudinally extending central axis, and the maincarrier member is located co-axially with the main central axis. In oneembodiment of the invention the inlet chamber is of transversecross-sectional area greater than that of the outlet chamber, and theprimary valve seat is formed by a step change in the cross-sectionalarea of the valve chamber between the outlet chamber and the inletchamber.

[0027] In another embodiment of the invention the transversecross-sectional area of the upstream chamber is greater than that of thedownstream chamber, and the secondary valve seat is formed by a stepchange in the cross-sectional area of the outlet chamber between thedownstream and the upstream chambers.

[0028] In one embodiment of the invention the valve housing defines anopen mouth to the valve chamber of transverse cross-sectional areasufficient to accommodate the primary and secondary valving members intothe valve chamber, and an end cap sealably engageable with the valvehousing closes the open mouth.

[0029] In another embodiment of the invention the primary valving memberextends around the main carrier member. Advantageously, the first andsecond secondary carrier members are located at respective opposite endsof the main carrier member.

[0030] In one embodiment of the invention the drive means comprises adrive motor, and a screw drive transmission between the drive motor andthe first secondary carrier member. Preferably, the drive shaft of thedrive motor is threaded for engaging a correspondingly threaded bore inthe first secondary carrier member for forming the screw drivetransmission. Advantageously, the drive motor and the screw drivetransmission define a rotational axis which coincides with the maincentral axis of the valve chamber.

[0031] In one embodiment of the invention a keying means keys the firstsecondary carrier member is keyed in the valve chamber for preventingrotation thereof as the screw drive transmission rotates for urging thefirst secondary carrier member longitudinally along the main centralaxis.

[0032] In one embodiment of the invention a main outlet port is locatedin the valve housing communicating with the downstream chamber of theoutlet chamber, and advantageously, a secondary outlet port is providedin the valve housing communicating with the upstream chamber of theoutlet chamber, and ideally, an inlet port is provided in the valvehousing communicating with the inlet chamber.

[0033] Ideally, the drive motor is provided by a stepper motor, andpreferably, comprises a permanent magnet rotor keyed to the drivetransmission, the rotor being located in the valve chamber, and a statorcomprising a plurality of electromagnetic stator coils being locatedradially around the rotor and being sealably isolated from the rotor.Advantageously, the stator coils are located in the end cap.

[0034] In one embodiment of the invention the valve is adapted forcontrolling the flow of a fluid therethrough.

[0035] In another embodiment of the invention the valve is adapted forcontrolling the flow of gas therethrough.

[0036] In a further embodiment of the invention the valve is adapted forcontrolling the flow of fuel gas therethrough.

[0037] In a still further embodiment of the invention the secondaryoutlet port is adapted for connecting to a pilot light jet of a gaspowered appliance, and the main outlet port is adapted for connection toa main burner of the gas appliance.

[0038] The advantages of the invention are many. A particularlyimportant advantage of the invention is that the valve according to theinvention is particularly suitable as a safety valve for use insupplying fuel gas to a gas appliance. In particular the valve accordingto the invention provides an on/off valve which incorporates a safetyfeature which facilitates instantaneous isolation of the fuel gas supplyto the gas appliance in the event of an emergency. This is due to thefact that the primary and secondary valving members can be selectivelydecoupled from the drive means for instantaneously urging the primaryand secondary valving members into engagement with the primary andsecondary valve seats. When a single first magnetic field generatingmeans is provided, the primary and secondary valving members aresimultaneously instantaneously decoupled from the drive means when thefirst magnetic field generating means is powered down, thereby, allowingthe primary and secondary valving members to be urged simultaneouslyinto engagement with the corresponding primary and secondary valve seatsby the urging means. A further advantage of the invention is achievedwhen a second magnetic field generating means is provided formagnetically coupling the secondary valving member to the drive means orto the first valving member, and the second magnetic field generatingmeans is independent of the first magnetic field generating means. Inwhich case, the primary and secondary valving members can beindependently decoupled from the drive means for selectively closing therespective primary and secondary passageways independently of eachother. This aspect of the invention provides a particular advantage whenthe valve is provided with a main outlet port whereby a fluid supply tothe main outlet port is controlled by both the primary and secondaryvalving means and a fluid supply to the secondary outlet port iscontrolled by the primary valving means only. In which case, by poweringdown the second magnetic field generating means only the secondaryvalving member is decoupled from the drive means for isolating the mainoutlet port from the fluid supply, while the primary valving member maybe retained by the first magnetic field generating means and the drivemeans for permitting the flow of fluid to the secondary outlet port.Thus, in cases where the valve according to the invention is providedfor controlling the supply of fuel gas to a gas powered appliance, ifthe main outlet port is connected to a main burner of the gas appliance,and the secondary outlet port is connected to a pilot light supply forthe main burner, the supply of fuel gas to the main burner can beisolated in the event of an emergency by powering down the secondmagnetic field generating means, while fuel gas can still be supplied tothe pilot light jet through the secondary outlet port.

[0039] A further advantage of the invention is that little power isdissipated as heat in the valve, and furthermore, the power requirementof the valve is significantly lower than that which is required by asolenoid operated valve. Furthermore, operation of the valve isrelatively silent by comparison to conventional solenoid valves, and thevalve is operable for regulating the flow of fluid therethrough withoutany mechanical hystersis.

[0040] The invention will be more clearly understood from the followingdescription of some preferred embodiments thereof which are given by wayof example only with reference to the accompanying drawings, in which:

[0041]FIG. 1 is a transverse cross-sectional side elevational view of avalve according to the invention,

[0042]FIG. 2 is a view similar to FIG. 1 of the valve of FIG. 1 in adifferent state,

[0043]FIG. 3 is a view similar to FIG. 1 of the valve of FIG. 1 inanother different state,

[0044]FIG. 4 is a view similar to FIG. 1 of the valve of FIG. 1 in astill further different state,

[0045]FIG. 5 is a view similar to FIG. 1 of a valve according to anotherembodiment of the invention,

[0046]FIG. 6 is a view similar to FIG. 5 of the valve of FIG. 5 in adifferent state, and

[0047]FIG. 7 is a view similar to FIG. 5 of the valve of FIG. 5 inanother different state.

[0048] Referring to the drawings and initially to FIGS. 1 to 4 thereof,there is illustrated a valve according to the invention indicatedgenerally by the reference numeral 1 which is particularly suitable forswitching a fuel gas supply to a gas powered appliance, for example, agas powered heater, a gas powered oven, a gas powered hob or the like,none of which are illustrated. The valve 1 comprises a valve housing 2of any suitable material, typically, aluminium which defines anelongated valve chamber 3 of circular stepped transverse cross-sectionalarea, which defines a main central axis 4. An inlet port 5 to the valvechamber 3 accommodates fuel gas into the valve chamber 3, and a mainoutlet port 6 and a secondary outlet port 7 accommodate fuel gas fromthe valve chamber 3. Typically, the main outlet port 6 is adapted fordelivering a fuel gas supply to a main burner of the gas poweredappliance, while the secondary outlet port 7 is adapted for delivering apilot supply of fuel gas to a pilot jet of the fuel gas appliance. Thisis described in more detail below. The valve housing 2 defines an openmouth 10 to the valve chamber 3 which is sealably closed by an end cap11. A sealing gasket 12 seals the end cap 11 to the valve housing 2.

[0049] A primary valve seat 15 is formed in the valve chamber 3 at astep change in the diameter of the valve chamber 3 by an annular lip 16which extends from the valve housing 2 at the step change in diameterinto the valve chamber 3. The primary valve seat 15 divides the valvechamber 3 into the inlet chamber 17 with which the inlet port 5communicates and an outlet chamber 18 from which the main and secondaryoutlet ports 6 and 7 extend. The primary valve seat 15 also defines aprimary communicating passageway 19 which communicates the inlet chamber17 with the outlet chamber 18. A secondary valve seat 20 is formed inthe outlet chamber 18 by an annular lip 21 which extends from the valvehousing 2 into the outlet chamber 18 at another step change in diameterof the valve chamber 3. The secondary valve seat 20 divides the outletchamber 18 into an upstream chamber 23 from which the secondary outletport 7 extends, and a downstream chamber 24 from which the main outletport 6 extends. The secondary valve seat 20 also defines a secondarypassageway 25 which communicates the upstream chamber 23 with thedownstream chamber 24.

[0050] A carrier means comprising a main carrier member 30, and a pairof first and second secondary carrier members 31 and 32, respectivelylocated at opposite ends of the main carrier member 30 are located inthe valve chamber 3, and the main carrier member 30 carries a primaryvalving member 35 for co-operating with the primary valve seat 15 forselectively closing the primary communicating passageway 19 forisolating the main and secondary outlet ports 6 and 7 from the inletport 5. The second secondary carrier member 32 carries a secondaryvalving member 36 for cooperating with the secondary valve seat 20 forselectively closing the secondary communicating passageway 25 forisolating the main outlet port 6 from the inlet port 5, and also fromthe secondary outlet port 7. The main carrier member 30 and the firstand second secondary carrier members 31 and 32 are of circulartransverse cross-section, and are co-axially located in the valvechamber 3 along the main central axis 4.

[0051] A drive means comprising a drive motor 38 located in the end cap11 as will be described below drives the main carrier member 30 axiallyin the valve chamber 3 through a screw drive transmission 39, for inturn urging the primary valving member 35 and the secondary valvingmember 36 out of and into engagement with the primary valve seat 15 andthe secondary valve seat 20, respectively, for opening and closing theprimary communicating passageway 19 and the secondary communicatingpassageway 25, respectively. A drive shaft 42 of the drive motor 38 isthreaded at 43 and co-operates with a threaded bore 44 extending throughthe first secondary carrier member 31 for forming the screw drivetransmission 39. A keying means comprising a keying pin 40 extendsdownwardly from the end cap 11 into the valve chamber 3, and slideablyengages a corresponding bore 41 in the first secondary carrier member 31for keying the first secondary carrier member 31 in the valve chamber 3for preventing rotation of the first secondary carrier member 31 duringdriving of the first secondary carrier member 31 and the main carrier 30by the drive motor 38.

[0052] The primary valving member 35 is provided by an annular seal 45which extends around the main carrier member 30, and is carried on aradially extending flange 46 which extends circumferentially around themain carrier member 30. The secondary valving member 36 comprises asealing disc 47 which is carried on a support disc 48. The support disc48 is in turn carried on the second secondary carrier member 32 as willbe described below.

[0053] The main carrier member 30 is machined from a single cylindricalmember of magnetic material, typically, steel, and comprises an outerupstream sleeve 50 and an outer downstream sleeve 51 which extend inopposite directions from a central body member 52 from which the flange46 extends. An upstream core member 54 extends from the central bodymember 52 within the outer upstream sleeve 50, while a downstream coremember 55 extends from the central body member 52 within the outerdownstream sleeve 51. An upstream central bore 58 extends into theupstream core member 54, while a downstream central bore 59 extends intothe downstream core member 55. The outer upstream and downstream sleeves50 and 51, the upstream and downstream core members 54 and 55, theupstream and downstream central bores 58 and 59, and the central bodymember 52 are all co-axial and are coaxial with the main central axis 4of the valve housing 2. The first and second secondary carrier members31 and 32 are also of magnetic material, typically, steel, and abutrespective ends of the outer upstream and downstream sleeves 50 and 51and the upstream and downstream core members 54 and 55, respectively,and form with the respective sleeves 50 and 51 and core members 54 and55 a magnetic circuit.

[0054] A first magnetic field generating means comprising a firstelectromagnetic coil 60 selectively magnetically couples the firstsecondary carrier member 31 with the main carrier member 30, and asecond magnetic field generating means comprising a secondelectromagnetic coil 61 selectively magnetically couples the secondsecondary carrier member 32 with the main carrier member 30 so that theprimary and secondary valving members 35 and 36 can be urged by thedrive motor 38 in the direction of the arrow A for opening the primaryand secondary passageways 19 and 25, and in the direction of the arrow Bfor closing the primary and secondary passageways 19 and 25,respectively. The first and second electromagnetic coils 60 and 61 arelocated in the main carrier member 30, and are wound on first and secondformers 63 and 64, respectively, which extend around the correspondingupstream and downstream core members 54 and 55, respectively, in annulidefined between the corresponding upstream and downstream sleeves 50 and51 and the upstream and downstream core members 54 and 55, respectively.The first coil 60 induces a magnetic field in the magnetic circuitformed by the main carrier member 30 and the first secondary carriermember 31 for retaining the first secondary carrier member 31magnetically coupled to the main carrier member 30 while the first coil60 is electrically powered. The second coil 61 induces a magnetic fieldin the magnetic circuit formed by the main carrier member 30 and thesecond secondary carrier member 32 for retaining the second secondarycarrier member 32 magnetically coupled to the main carrier member 30while the second coil 61 is electrically powered.

[0055] A first urging means comprising a pair of concentric firstcompression springs, namely, a first inner compression spring 65 and afirst outer compression spring 66 urges the main carrier member 30axially in the direction of the arrow B for in turn urging the primaryand secondary valving members 35 and 36 into engagement with the primaryand secondary valve seats 15 and 20, respectively, for closing theprimary and secondary communicating passageways 19 and 25, when thefirst and second coils 60 and 61 are powered down and the first andsecond secondary carrier members 31 and 32 are magnetically decoupledfrom the main carrier member 30. The first inner and outer compressionsprings 65 and 66 are concentric with the main central axis 4, and actbetween the end cap 11 and the main carrier 30 for urging the primaryand secondary valving members 35 and 36 into engagement with the primaryand secondary valve seats 15 and 20. The first inner and outercompression springs 65 and 66 are electrically conductive and also actas conducting means for independently connecting the respective firstand second coils 60 and 61 to corresponding first and second externalterminals 68 and 69 for selectively and independently supplyingelectrical power to the first and second coils 60 and 61. First andsecond connectors 78 and 79 extending through the gasket 12 connect therespective first inner and outer compression springs 65 and 66 to thecorresponding first and second external terminals 68 and 69,respectively. The gasket 12 is of an electrically insulating material.First and second electrical conductors 73 and 74 extend throughcorresponding slots 75 and 76 in the main carrier member 30 forelectrically connecting the first inner and outer compression springs 65and 66 to the corresponding first and second coils 60 and 61. The firstinner and outer springs 65 and 66 bear on the corresponding first andsecond connectors 78 and 79 and the corresponding first and secondconductors 73 and 74 for providing electrical continuity from the firstexternal terminal 68 to the first coil 60, and from the second externalterminal 69 to the second coil 61. The first and second conductors 73and 74 are insulated relative to the main carrier member 30.

[0056] The first and second electromagnetic coils 60 and 61 areelectrically connected to the central body member 52 by correspondingfirst and second conductors 70 and 71. In this way the electricalcircuits to the first and second electromagnetic coils 60 and 61 iscompleted through the central body member 52, and in turn through themain carrier member 30, the first secondary carrier member 31, the driveshaft 42 of the motor 38 and the end cap 11. Thus, the end cap 11, thedrive shaft 42, the first secondary carrier member 31 and the maincarrier member 30 act as a ground or earth for the respective first andsecond coils 60 and 61. Accordingly, the first and secondelectromagnetic coils 60 and 61 can be selectively powered downindependently of each other for facilitating selective magneticdecoupling of the second secondary carrier member 32 from the maincarrier member 30 and the main carrier member 30 from the firstsecondary carrier member 31, respectively, for in turn selectively andindependently urging the secondary valving member 36 into engagementwith the secondary valve seat 20, and the primary valving member 35 intoengagement with the primary valve seat 15.

[0057] A second urging means comprising a second compression spring 80acting between the former 64 in the main carrier member 30 and thesecond secondary carrier member 32 urges the second secondary carriermember 32 from the main carrier 30, for in turn urging the secondaryvalving member 36 into engagement with the secondary valve seat 20 whenthe second electromagnetic coil 61 has been powered down and the secondsecondary carrier member 32 has been magnetically decoupled from themain carrier member 30.

[0058] The support disc 48 which supports the sealing disc 47 of thesecondary valving member 36 is carried on a spindle 81 which extendsthrough a bore 84 in the second secondary carrier member 32 into thedownstream central bore 59 of the main carrier member 30. The spindle 81is slideable in the bore 84 and in the downstream central bore 59, andis retained in the downstream central bore 59 in the main carrier 30 bythe magnetic field in the main carrier member 30 and the secondsecondary carrier member 32 while the second electromagnetic coil 61 ispowered up. The support disc 48 is also slideable on the spindle 81, anda secondary compression spring 85 acting between the second secondarycarrier member 32 and the support disc 48 urges the support disc 48towards the free end of the spindle 81 for, in turn, resiliently urgingthe secondary valving member 36 relative to the second secondary carriermember 32 into engagement with the secondary valve seat 20.

[0059] Turning now to the drive motor 38, the drive motor 38 is astepper motor and comprises a permanent magnet rotor 86 rigidly securedto the drive shaft 42. The drive shaft 42 is rotatably carried inbearings at 87 and 88 in a shaped portion 89 of the end cap 11. Fourradially extending stator coils 90 arranged at 90° intervals around therotor 86 are located externally of the shaped portion 89 in the end cap11 for rotating the rotor 86, and in turn the drive shaft 42. Terminals91 extending from the end cap 11 are connected to the stator coils 90for powering the stator coils 90. The end cap 11 is so arranged that achamber 92 in the shaped portion 89 within which the rotor 86 is locatedis completely sealed from the stator coils 89, and accordingly, gaspassing through the bearing at 88 from the valve chamber 3 is sealablyretained in the chamber 92. The upstream central bore 58 in the mainbody member 30 accommodates the threaded portion 43 of the drive shaft42 as the first and second secondary carrier member 31 and 32 and themain carrier member 30 when magnetically coupled are being urged in thedirection of the arrow A by the drive motor 38 for opening therespective primary and secondary communicating passageways 19 and 25.The annulus formed between the upstream outer sleeve 50 and the upstreamcore member 54 similarly accommodates the keying pin 40 as the first andsecond secondary carrier member 31 and 32 and the main carrier member 30are being urged in the direction of the arrow A. An electricallyinsulating disc 94 in the end cap 11 spaces apart and electricallyinsulates the first and second terminals 68 and 69 and the terminals 91of the stator coils from each other.

[0060] The operation of the valve 1 will now be described. Typically,where the valve 1 is provided for supplying fuel gas to a gas poweredappliance, the main outlet port 6 is connected to a burner of the gaspowered appliance, while the secondary outlet port 7 is connected to apilot jet associated with the burner of the gas powered appliance. Afuel gas supply is connected to the inlet port 5. An electrical powersupply is connected to the terminals 68, 69 and 91. The power supply tothe terminals 68 and 69 to the first and second electromagnetic coils 60and 61, respectively, typically is supplied through respectivecorresponding switches (not shown), which may, for example, be operatedunder the control of respective thermostats (also not shown) formonitoring the temperature of the gas powered appliance. The powersupply to the terminals 91 of the stator coils 90 is typically suppliedthrough a control switch (not shown) for operating the stepper motor 38for opening and closing the primary and secondary passageways 19 and 25by respectively disengaging and engaging the primary and secondaryvalving members 35 and 36 with the primary and secondary valve seats 15and 20, respectively, and also for modulating the flow of fuel gasthrough the primary and secondary passageways 19 and 25.

[0061] In normal operation the first and second electromagnetic coils 60and 61 are powered up, thereby magnetically coupling the first andsecond secondary carrier members 31 and 32 with the main carrier member30. Accordingly, in normal operation when the valve is closed with theprimary and secondary valving members 35 and 36 engaged with the primaryand secondary valve seats 15 and 20, the main and secondary outlet ports6 and 7 are isolated from the main inlet port 5, see FIG. 1. When thevalve 1 is in this state and when the first and secondary coils 60 and61 are powered up, thereby magnetically coupling the first and secondsecondary carrier members 31 and 32 with the main carrier 30, when it isdesired to open the valve to communicate the main and secondary outletports 6 and 7 with the inlet port 5, the stepper motor 38 is operatedfor urging the main carrier member 30 in the direction of the arrow Afor in turn disengaging the primary valving member 35 and the secondaryvalving member 36 from the primary and secondary valve seats 15 and 20.Because of the secondary compression spring 85 which urges the secondaryvalving member along the spindle 81 into engagement with the secondaryvalving seat 20, as the main carrier member 30 is being urged in thedirection of the arrow A, the primary valving member 35 disengages theprimary valve seat 15, while the secondary valving member 36 remains inengagement with the secondary valve seat 20. The secondary valvingmember 36 remains in engagement with the secondary valve seat 20 untilthe secondary valving member 36 has slid along the spindle 81 under theaction of the secondary compression spring 85 to the free end thereof.At which stage, further movement of the main carrier member 30 in thedirection of the arrow A causes the secondary valving member 36 todisengage the secondary valve seat 20, thereby opening the primary andsecondary passageways 19 and 25, and thus the valve 1, see FIG. 2. Inthis way a supply of fuel gas is supplied through the secondary outletport 7 to the pilot jet, which can be ignited prior to the fuel gassupply being delivered through the main outlet port 6 to the burner. Thestepper motor 38 can then be operated for urging the main carrier member30 in the direction of the arrow A or B for modulating the flow of fuelgas through the main outlet port 6, depending on the rate at which fuelgas is to be delivered to the burner through the outlet port 6. When itis desired to isolate the burner and the pilot jet from the fuel gassupply, the stepper motor 38 is operated for urging the main carriermember 30 in the direction of the arrow B for in turn engaging theprimary and secondary valving members 35 and 36 with the correspondingprimary and secondary valve seats 15 and 20, thus closing the valve 1.During this entire operation from the time the valve 1 is opened untilit is closed, the first and second coils 60 and 61 were continuouslypowered.

[0062] If during normal operation of the valve 1 while the valve 1 issupplying fuel gas to the burner and the pilot jet through the main andsecondary outlet ports 6 and 7, should an emergency arise, for example,should the temperature of the gas powered appliance rise above a safelevel, the respective switches (not shown) through which the electricalpower supply is supplied to the first and second coils 60 and 61 areswitched off under the action of the respective thermostats (not shown),thereby isolating the first and second coils 60 and 61 from the powersupply. Once the first and second coils 60 and 61 are powered down, thefirst and second secondary carrier members 31 and 32 are effectivelyinstantaneously magnetically decoupled from the main carrier member 30.Thus, the secondary valving member 36 is virtually instantaneously urgedin the direction of the arrow B into engagement with the secondary valveseat 20 under the action of the second compression spring 80 actingbetween the main carrier member 30 and the second secondary carriermember 32. Simultaneously the main carrier member 30 is urged in thedirection of the arrow B by the first inner and outer springs 65 and 66for in turn simultaneously urging the primary valving member 35 intoengagement with the primary valve seat 15, see FIG. 3. Thus, the fuelgas supply is virtually instantly isolated from the main and secondaryoutlet ports 6 and 7, and in turn from the burner and pilot jet of thegas powered appliance being supplied by the valve 1.

[0063] Should the valve 1 be closed in an emergency as just described,in order to open the valve 1, and to operate the valve 1 normally, thestepper motor 38 must first be operated for urging the first secondarycarrier member 31 in the direction of the arrow B for engaging the maincarrier member 30, and further, for urging the main carrier member 30into engagement with the second secondary carrier member 32. When thefirst and second secondary carrier members 31 and 32 are in tightabutting engagement with the main carrier member 30 the power supply tothe first and second coils 60 and 61 is again established, therebymagnetically coupling the first and second secondary carrier members 31and 32 with the main carrier member 30. For so long as the first andsecond coils 60 and 61 continue to be powered, the main body member 30,and in turn the primary and secondary valving members 35 and 36 can beoperated in the directions of the arrows A and B by the stepper motor 38for opening and closing the valve 1 and for modulating the flow of fuelgas through the valve 1.

[0064] In certain cases, should it be desired to only isolate the mainoutlet port 6 from the inlet port 5 in an emergency, the switch (notshown) supplying the second coil 61 can be switched off, therebyisolating the second coil 61 from the power supply, and thusmagnetically decoupling only the second secondary carrier member 32 fromthe main carrier member 30. This, thus, causes the secondary valvingmember 36 to be urged in the direction of the arrow B into engagementwith the secondary valve seat 20 under the action of the secondcompression spring 80 acting between the main carrier member 30 and thesecond secondary carrier member 32, see FIG. 4. In order to operate thevalve normally by the stepper motor 38 after the second coil 61 has beenisolated from the electrical power supply, the stepper motor 38 isoperated for urging the first secondary carrier member 31 and the maincarrier member 30 in the direction of the arrow B for urging the maincarrier member 30 into engagement with the second secondary carriermember 32 so that by providing the electrical power supply to the secondcoil 61 the main carrier member 30 and the second secondary carriermember 32 can be again magnetically coupled.

[0065] It should be noted that the combined urging force of the firstinner and outer compression springs 65 and 66 should be greater than theurging force of the second compression spring 80 for avoiding any dangerof the second compression spring 80 acting against the first inner andouter compression springs 65 and 66 for urging the primary valvingmember 35 out of engagement with the primary valve seat 15 when thevalve 1 is closed under the action of the respective compression springs65, 66 and 80 when the main carrier member 30 is disengaged from thefirst secondary carrier member 31.

[0066] Referring now to FIGS. 5 to 7 there is illustrated a valve 100according to another embodiment of the invention. The valve 100 issubstantially similar to the valve 1, and similar components areidentified by the same reference numerals. The main difference betweenthe valve 100 and the valve 1 is that the second electromagnetic coil 61and the corresponding second former 64 have been dispensed with.However, the magnetic field generated by the first electromagnetic coil60 is sufficient for retaining the first and second secondary carriermembers 31 and 32 magnetically coupled with the main carrier member 30.In order to establish a magnetic circuit for magnetically coupling thefirst and second secondary carrier members 31 and 32 with the maincarrier member 30, the annuli formed between the outer upstream anddownstream sleeves 50 and 51 and the upstream and downstream coremembers 54 and 55 extend continuously through the main carrier member 30and through the central body member 52. An annular member 101 ofnon-magnetic material, in this embodiment of the invention brass,extends within the annulus formed between the outer downstream sleeve 51and the downstream core member 55 for locating the respective outerupstream and downstream sleeves 50 and 51 and the upstream anddownstream core members 54 and 55 relative to each other. The annularmember 101 extends into the central body member 52. The secondcompression spring 80 acts between the annular member 101 and the secondsecondary carrier member 32. O-ring seals 103 seal the annular member101 within the main carrier member 30 for preventing the flow of fluidfrom the inlet chamber 17 to the outlet chamber 18 through the maincarrier member 30. In this embodiment of the invention the first coil 60is powered through the first inner and outer compression springs 65 and66.

[0067] Operation of the valve 100 is substantially similar to operationof the valve 1 with the exception that it is not possible tomagnetically decouple the second secondary carrier member 32 from themain carrier member 30 independently of decoupling the main carriermember 30 from the first secondary carrier member 31. Once the firstelectromagnetic coil 60 is powered down, the first and second secondarycarrier members 31 and 32 are simultaneously magnetically decoupled fromthe main carrier member 30.

[0068] In FIG. 6 the valve 100 is illustrated with the primary andsecondary valving members 35 and 36 engaging the primary and secondaryvalve seats 15 and 20 thus closing the primary and secondary passageways19 and 25. In FIG. 6 the main carrier member 30 has been moved into thisclosed position by the stepper motor 38. In FIG. 7 the main carriermember 30 and the primary and secondary valving members 35 and 36 areillustrated in a similar position to that of FIG. 6, however, in FIG. 7the main carrier member 30 has been urged into the closed position underthe action of the first inner and outer compression springs 65 and 66 asa result of magnetic decoupling of the main carrier member 30 from thefirst secondary carrier member 31, resulting from powering down of thefirst coil 60. In FIG. 5 the valve 100 is illustrated open with the maincarrier member 30 magnetically coupled to the first secondary carriermember 31 and held in the open position by the stepper motor 38.

[0069] The advantage of providing the drive means as a stepper motor 38is that it permits precision control of axial movement of the maincarrier member 30 in the direction of the arrows A and B for in turnproviding precision control and modulation of the flow of fuel gasthrough the main and secondary outlet ports, and in particular, throughthe main outlet port for modulating the flow of fuel gas supply to theburner. This is achieved by the fact that the number of steps throughwhich the stepper motor 38 is rotated can be counted, thereby allowing aprecise determination of the position of the main carrier member 30 inthe valve chamber 3, and in turn, the positions of the primary andsecondary valving members 35 and 36 relative to the correspondingprimary and secondary valve seats 15 and 20 at any time during operationof the valves according to the invention.

[0070] A further advantage of the valves according to the invention isthat the valves cannot be opened for so long as the electromagnetic coilor coils are powered down, and irrespective of the position of the maincarrier member 30 in the valve chamber 5, once the electromagnetic coilor coils are powered down the valve will automatically be closed.

[0071] While the valves according to the invention have been describedgenerally as controlling the flow of fuel gas to a gas poweredappliance, it will be appreciated that the valves according to theinvention may be used for controlling any fluid or fluid like medium.

[0072] It will also be appreciated that while the keying means forpreventing rotation of the first secondary carrier member within thevalve chamber has been described as comprising a keying pin engageablewith a corresponding bore in the first secondary carrier member, anyother suitable keying means may be provided. For example, it isenvisaged that the first secondary carrier member may be appropriatelyshaped, for example, may be provided with one or more flats which wouldbe engageable with corresponding flats in the housing of the valve.

1. A valve comprising a valve housing (2) defining a valve chamber (3),the valve chamber (3) forming an inlet chamber (17) and an outletchamber (18), a primary valve seat (15) separating the inlet chamber(17) from the outlet chamber (18) and defining a primary communicatingpassageway (19) communicating the inlet chamber (17) with the outletchamber (18), a primary valving member (35) in the valve chamber (3)co-operating with the primary valve seat (15) for selectively closingthe primary communicating passageway (19) for isolating the outletchamber (18) from the inlet chamber (17), a secondary valve seat (20)located in the outlet chamber (18) downstream of the primary valve seat(15), the secondary valve seat (20) dividing the outlet chamber (18)into an upstream chamber,(23) and a downstream chamber (24) and defininga secondary communicating passageway (25) communicating the downstreamchamber (24) with the upstream chamber (23), a secondary valving member(36) being provided in the outlet chamber (18) cooperating with thesecondary valve seat (20) for closing the secondary communicatingpassageway (25) for isolating the downstream chamber (24) from theupstream chamber (23), the secondary valving member (36) being coupledwith the primary valving member (35), a drive means (38) releasablymagnetically coupleable to the primary valving member (35) for urgingthe primary valving member (35) and the secondary valving member (36)out of engagement with th primary valve seat (15) and the secondaryvalve seat (20), respectively, for respectively opening the primarycommunicating passageway (19) for communicating the respective inlet andoutlet chambers (17,18), and the secondary communicating passageway (25)for communicating the downstream chamber (24) with the upstream chamber(23), the drive means (38) and the primary valving member (35) beingselectively decoupleable, and a first urging means (65,66) beingprovided for urging the primary valving member (35) into engagement withthe primary valve seat (15) and the secondary valving member (36) intoengagement with the secondary valve seat (20) when the primary valvingmember (35) is decoupled from the drive means (38), characterised inthat the secondary valving member (36) is releasably magneticallycoupleable to the primary valving member (35), and a second urging means(80) is provided for urging the secondary valving member (36) intoengagement with the secondary valve seat (20) when the secondary valvingmember (36) is decoupled from the primary valving member (35).
 2. Avalve as claimed in claim 1 characterised in that the secondary valvingmember (36) is selectively decoupleable from the primary valving member(35).
 3. A valve as claimed in claim 1 or 2 characterised in that thesecondary valving member (36) is selectively decoupleable from theprimary valving member (35) independently of decoupling of the primaryvalving member (35) from the drive means (38).
 4. A valve as claimed inany preceding claim characterised in that the primary and secondaryvalving members (35,36) are sequentially urged out of engagement withthe respective primary and secondary valving seats (15,20) by the drivemeans (38) when the primary valving member (35) is magnetically coupledto the drive means (38) and the secondary valving member (36) ismagnetically coupled to the primary valving member (35).
 5. A valve asclaimed in claim
 4. characterised in that the primary valving member(35) is urged out of engagement with the primary valve seat (15) beforethe secondary valving member (36) is urged out of engagement with thesecondary valve seat (20).
 6. A valve as claimed in any preceding claimcharacterised in that the primary valving member (35) is carried on amain carrier member (30), and the drive means (38) is co-operable with afirst secondary carrier member (31), the first secondary carrier member(31) forming with the main carrier member (30) a magnetic circuit, and afirst magnetic field generating means (60,61) is provided forselectively generating a magnetic field for selectively coupling themain carrier member (30) and the first secondary carrier member (31). 7.A valve as claimed in claim 6 characterised in that a second secondarycarrier member (32) is provided for carrying the secondary valvingmember (36), the second secondary carrier member (32) forming a magneticcircuit with the main carrier member (30) for facilitating releasablemagnetic coupling of the second secondary carrier member (32) with themain carrier member (30).
 8. A valve as claimed in claim 7 characterisedin that the first and second secondary carrier members (31,32) arelocated at respective opposite ends of the main carrier member (30). 9.A valve as claimed in claim 7 or 8 characterised in that a secondmagnetic field generating means (61) is provided for selectivelymagnetically coupling the second secondary carrier member (32) with themain carrier member (30) independently of the magnetic coupling of themain carrier member (30) with the first secondary carrier member (31).10. A valve as claimed in any of claims 7 to 9 characterised in that thesecond urging means (80) acts between the main carrier member (30) andthe second secondary carrier member (32).
 11. A valve as claimed in anyof claims 7 to 10 characterised in that the secondary valving member(36) is resiliently mounted-to the second secondary carrier member (32)for facilitating relative movement between the second secondary carriermember (32) and the secondary valving member (36) for facilitatingdisengagement of the primary valving member (35) from the primary valveseat (15) prior to disengagement of the secondary valving member (36)from the secondary valve seat (20).
 12. A valve as claimed in any ofclaims 7 to 11 characterised in that each magnetic field generatingmeans (60,61) is an electrically-powered magnetic field generatingmeans.
 13. A valve as claimed in claim 12 characterised in that anelectrically conductive connecting means (65,66) is provided forconnecting each magnetic field generating means (60,61) to an electricalpower supply externally of the valve (1).
 14. A valve as claimed inclaim 12 or 13 characterised in that the respective first and secondmagnetic field generating means (60,61) are independently connected tothe external power supply by the electrically conductive connectingmeans (65,66).
 15. A valve as claimed in any of claims 12 to 14characterised in that the first magnetic field generating means (60)comprises a first electromagnetic coil (60) associated with the maincarrier member (30) and the first secondary carrier member (31).
 16. Avalve as claimed in any of claims 12 to 15 characterised in that thesecond magnetic field generating means (61) comprises a secondelectromagnetic coil (61) associated with the main carrier member (30)and the second secondary carrier member (32).
 17. A valve as claimed inany of claims 7 to 16 characterised in that the first magnetic fieldgenerating means (60) selectively couples the second secondary carriermember (32) with the main carrier member (30).
 18. A valve as claimed inany of claims 6 to 17 characterised in that the first urging means(65,66) acts between the valve housing (2) and the main carrier member(30) for urging the primary valving member (35) into engagement with theprimary valve seat (15).
 19. A valve as claimed in any of claims 6 to 18characterised in that the first urging means (65,66) comprises a pair offirst compression springs (65,66).
 20. A valve as claimed in claim 19characterised in that the respective first compression springs (65,66)are electrically conductive and are electrically mutually insulated foracting as the connecting means for connecting the first magnetic fieldgenerating means (60) to the external electrical power supply.
 21. Avalve as claimed in claim 19 or 20 characterised in that the respectivefirst compression springs (65,66) independently connect the respectivefirst and second magnetic field generating means (60,61) to the externalelectrical power supply.
 22. A valve as claimed in any of claims 19 to21 characterised in that the first compression springs (65,66) areconcentrically mounted.
 23. A valve as claimed in any of claims 6 to 22characterised in that the second urging means (80) comprises a secondcompression spring (80).
 24. A valve as claimed in any of claims 6 to 23characterised in that the valve chamber (3) is an elongated chamber, andthe main carrier member (30) is an elongated member extendinglongitudinally in the valve chamber (3) through the primarycommunicating passageway (19) from the inlet chamber (17) to the outletchamber (18).
 25. A valve as claimed in claim 24 characterised in thatthe valve chamber (3) is of circular transverse cross-section defining amain longitudinally extending central axis (4), and the main carriermember (30) is located co-axially with the main central axis (4).
 26. Avalve as claimed in any of claims 6 to 25 characterised in that theinlet chamber (17) is of transverse cross-sectional area greater thanthat of the outlet chamber (18), and the primary valve seat (15) isformed by a step change in the cross-sectional area of the valve chamber(3) between the outlet chamber (18) and the inlet chamber (17).
 27. Avalve as claimed in any of claims 6 to 26 characterised in that thetransverse cross-sectional area of the upstream chamber (23) is greaterthan that of the downstream chamber (24), and the secondary valve seat(20) is formed by a step change in the cross-sectional area of theoutlet chamber (18) between the downstream and the upstream chambers(23,24).
 28. A valve as claimed in any of claims 6 to 27 characterisedin that the valve housing (2) defines an open mouth (10) to the valvechamber (3) of transverse cross-sectional area sufficient to accommodatethe primary and secondary valving members (35,36) into the valve chamber(3), and an end cap (11) sealably engageable with the valve housing (2)closes the open mouth (10).
 29. A valve as claimed in any of claims 6 to28 characterised in that the primary valving member (35) extends aroundthe main carrier member (30).
 30. A valve as claimed in any of claims 6to 29 characterised in that the drive means (38) comprises a drive motor(38), and a screw drive transmission (39) between the drive motor (38)and the first secondary carrier member (31).
 31. A valve as claimed inclaim 30 characterised in that the drive shaft (42) of the drive motoris threaded (43) for engaging a correspondingly threaded bore (44) inthe first secondary carrier member (31) for forming the screw drivetransmission (39).
 32. A valve as claimed in claim 30 or 31characterised in that the drive motor (38) and the screw drivetransmission (39) define a rotational axis which coincides with the maincentral axis (4) of the valve chamber (3).
 33. A valve as claimed in anyof claims 30 to 32 characterised in that a keying means (40,41) keys thefirst secondary carrier member (31) in the valve chamber (3) forpreventing rotation thereof as the screw drive transmission (39) rotatesfor urging the first secondary carrier member(31) longitudinally alongthe main central axis (4).
 34. A valve as claimed in any preceding claimcharacterised in that a main outlet port (6) is located in the valvehousing (2) communicating with the downstream chamber (24) of the outletchamber (18).
 35. A valve as claimed in any preceding claimcharacterised in that a secondary outlet port (7) is provided in thevalve housing (2) communicating with the upstream chamber (23) of theoutlet chamber (18).
 36. A valve as claimed in any preceding claimcharacterised in that an inlet port (5) is provided in the valve housingcommunicating with the inlet chamber (17).
 37. A valve as claimed in anypreceding claim characterised in that the drive motor is a steppermotor.
 38. A valve as claimed in any preceding claim characterised inthat the drive motor (38) comprises a permanent magnet rotor (86) keyedto the drive transmission (39), the rotor (86) being located in thevalve chamber (3), and a stator (90) comprising a plurality ofelectromagnetic stator coils (90) being located radially around therotor (86) and being sealably isolated from the rotor (86).
 39. A valveas claimed in claim 38 characterised in that the stator coils (90) arelocated in the end cap (11).
 40. A valve as claimed in any precedingclaim characterised in that the valve (1) is adapted for controlling theflow of a fluid therethrough.
 41. A valve as claimed in any precedingclaim characterised in that the valve (1) is adapted for controlling theflow of gas therethrough.
 42. A valve as claimed in any preceding claimcharacterised in that the valve (1) is adapted for controlling the flowof fuel gas therethrough.
 43. A valve as claimed in any preceding claimcharacterised in that the secondary outlet port (7) is adapted forconnecting to a pilot light jet of a gas powered appliance, and the mainoutlet port (6) is adapted for connection to a main burner of the gasappliance.